A Government jet and a maritime patrol plane are standing by in Malta today for a possible emergency evacuation of Irish citizens trapped in Libya.

The Air Corp's Learjet 45, which can take up to seven passengers, and a Casa 235 patrol plane, which can carry up to 44 passengers, took off from Baldonnel aerodrome within an hour of each other last night. Their deployment was approved by Taoiseach and Foreign Affairs Minister Brian Cowen.

The decisions follow increasing concern about the safety of about 40 Irish people who remain in the country, after the latest assessment of the deteriorating political situation there.

It is understood that provisional plans are in place to evacuate the group. But it depends on security on the ground and an accurate reading of the situation on roads and at the airport.

A small group of Irish nationals escaped from the capital on a commercial airliner to Istanbul yesterday, one of the few flights in recent days.

A number of EU countries are trying to organise flights for their citizens out of Tripoli and it is hoped the remaining Irish citizens will be included on these.

However, chaos has ensued at the airport, as about 7,000 people attempt to leave by air.

"In order to land, the flights need flight clearance. In order to get flight clearance, you have got to deal with the Libyan authorities. It is a very, very confused situation," a spokesman for the department said.

A group of between four and seven Irish teachers left Tripoli for Istanbul yesterday. Some more Irish nationals were reported to be on board other flights last night.

This leaves about 30 Irish people, who want to leave the country, in and around Tripoli. Another five are in the Benghazi region, where fighting broke out at the weekend.

Dublin City University lecturer Helena Sheehan is among those still in Tripoli. She was there to give a lecture but it was subsequently cancelled. She is supposed to travel home tomorrow.